1. Field of Technology
The present invention relates to a throttle valve control apparatus for an internal combustion engine which drives a motor vehicle, whereby a degree of the throttle valve opening is controlled in accordance with an accelerator pedal actuation.
2. Background Technology
A throttle valve control apparatus for an internal combustion engine is known in the prior art, whereby the actuation position of an accelerator pedal is detected and a throttle valve is driven in accordance with the relationship between the detected actuation position and a predetermined throttle valve opening degree characteristic (Japanese Patent Laid-open No. 59-99045). Furthermore, a throttle valve control apparatus has been described (Japanese Patent Laid-open No. 59-74341), whereby a plurality of different throttle valve opening degree characteristics relating to an accelerator pedal actuation position are stored in a memory beforehand, and an opening degree characteristic is manually selected from among these stored characteristics by means such as a switch.
With such a prior art throttle valve control apparatus in which a manual selection of the throttle valve opening degree characteristic is performed, the opening degree characteristic can be selected, for example, so as to place emphasis upon improved control of the engine output power under a condition of low load operation. However, if the vehicle driver rapidly depresses the accelerator pedal in order to produce rapid acceleration so that emphasis is placed upon improved control under a low load operation, then the vehicle will operate so as to provide an impression of comparatively poor response to the demand for acceleration. Conversely, if the throttle valve opening degree characteristic is selected so as to emphasize excellent acceleration capability, then it will be difficult to achieve a fine degree of control of the engine output power by means of the accelerator pedal. These disadvantages can clearly be avoided if the throttle valve opening degree characteristic is selected so as to be appropriate for the current running condition of the vehicle. However, it would be difficult for the driver to continuously select the most suitable throttle valve opening degree characteristic during vehicle operation, so that in fact such a method would lead to a lowering of engine performance.